Effects of Non-Darcy Flow on The Impairment of Gas Condensate Wells

Jonah, Emmanuel Abah (2017-12-10)

Main Thesis


Gas condensate reservoirs are initially discovered as single-phase gas reservoirs. As the reservoir is produced below the fluid dew-point pressure, an increase in condensate saturation in the near wellbore region occur which reduces the relative permeability to gas and in turn causes productivity impairment. It is pertinent to predict condensate banking behavior due to Non-Darcy effects accurately during a field’s operational phase to avoid problems with a well’s ability to attain production targets. This paper therefore seeks to evaluate the effect of Non-Darcy flow on the impairment of gas condensate wells. This paper seeks to evaluate the effects of Non-Darcy flow on the impairment of gas condensate by varying the degree of Turbulence through adopting various Forchheimer factors. To achieve this, a PVT data for gas condensate reservoir from a field was used to build an input data file using Eclipse. 300. A single-layer, radial, 3D reservoir model was used to investigate the effects of Non-Darcy on field gas flow rates and cumulative gas produced over the life span of the well. A fully perforated vertical well was located at the center of the reservoir model. The reservoir model consisted of 30 grid blocks increasing logarithmically with radius away from the well bore.The use of fine-resolution griding near the well bore was to ensure that change in condensate was accurately simulated. The results showed that When Velocity Dependent Relative Permeability (VELDEP) option was adopted for Forchheimer of 10 there was no significance change in the gas production rate. However, when the factor increases to 100, There exist a significant increase in the gas production rate as well as the cumulative field production. Also productivity of the well decreases by about 22% during the first three years of production due to skin effect arising from increased turbulence around the well-bore region